Dolomite lime & Greenleaf Chellated Iron

I was in the gardening supply store today searching for stuff and
came across Chellated Iron powder which is selling for about $10
Cdn for about a pound of it. I don't think there are any other
trace elements in it but this is much lower cost than the chellated
nutrient mix we've been using to-date for PMDD. It's made locally
in Vancouver by Greenleaf but I didn't write down any details 
(lacked pen).

I was also looking for granular dolomite but all I could find was
a box of dolomite lime. This is primarily calcium carbonate and
magnesium carbonate and can be used in small amounts to add
calcium and magnesium to soft water. Calcium shortages can easily
occur with soft water unless you add it.

I'm thinking about mixing some of the dolomite powder with clay
for the bottom layer of my substrate but don't have any guidelines
for how much would be advisable. Since this is a powder form, if
it were to come into contact with a significant amount of water,
it will dissolve quickly. I think this won't be a problem if its
confined to the substrate esp to a less permeable clay layer.

Q - Has anyone used dolomite lime in powder form in a substrate?
How much and what were your results?

I'll probably keep the dolomite powder around for regular additions
in small amounts during water changes. I think it will be
better to use finely ground up egg shells and crushed sterilized
sea shells in the substrate as a calcium source.

WARNING: please be very conservative when you're experimenting
with putting things into your aquarium. It's best to leave
experimentation to the experts or those with less common sense.
(not sure which category I'm in ;-) It takes several months
to determine the effects of substrate materials and its very
easy to be mislead by a multitude of factors which come into

Steve Pushak       in drizzly Vancouver BC